Reality check: Does eating potatoes four times a week really put you at risk of hypertension?

Fried, baked and mashed – potatoes are a pretty common Canadian staple. But a new study is warning that eating potatoes four times a week could be increasing your risk of high blood pressure.

The findings are controversial though, with critics suggesting the results shouldn’t stop Canadians from eating potatoes if they’re prepared healthily.

The latest findings come out of the Harvard School of Public Health and Brigham and Women’s Hospital.

The team of researchers followed more than 186,000 people through three longitudinal studies conducted in the U.S. (the Nurses’ Health Study, the Nurses’ Health Study II and the Health Professionals Follow-up Study).

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“In our observational study, participants who did not have high blood pressure at baseline, and consumed four or more servings a week of potatoes – boiled, baked or mashed – later had a higher risk of developing hypertension compared to those who consumed one or less than one serving a month,” lead author, Dr. Lea Borgi, said.

“Additionally, we found that if a participant replaced one serving of boiled, baker or mashed potato per day with a non-starchy vegetable, it was associated with a lower risk of hypertension,” she explained.

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Compared to people who had only one serving of potatoes per month, those who had four or more servings increased their risk of high blood pressure by 11 per cent for boiled, baked or mashed potatoes. The risk increased to 17 per cent for French fries.

The study participants had to self-report their diet and eating habits, though. That’s what makes the findings concerning, according to Dr. Katherine Gottschall-Pass, a food and nutrition professor at the University of Prince Edward Island. She’s chair of the university’s applied sciences department

“It’s really difficult to get exact measures from that because people are relying on memory. You come up with a number but whether that’s an accurate number or not is hard to say,” she told Global News.

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The case applies to reporting hypertension, too. Perhaps a family doctor told the study participants that high blood pressure was a concern – he or she could have said they had hypertension on the questionnaire based on that red flag.

The other issue is that it’s unclear what these people were eating with potatoes. It’s a gaping hole for Gottschall-Pass.

“They don’t measure salt and we know sodium has a strong correlation with hypertension. When people eat potatoes, they tend to put sour cream, butter or margarine and salt on them. If you’re eating more potatoes, you’re probably eating more salt and these ingredients,” Gottschall-Pass warned.

Australian researchers agree – their issue with the findings is that they zero in on one food instead of looking at the bigger picture.

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“It is more important to look at the whole diet of a person rather than demonise the potato. I do not think it is a good idea to tell people to avoid healthier ways of cooking potatoes,” Dr. Rebecca Reynolds, a nutritionist and lecturer from the University of New South Wales, told Australian outlets.

For their part, the authors concede that other factors could be at play, too.

“We take into account all of the data that are available to us and make the relevant statistical adjustments. However, because this is an observational study, there is always a possibility that our findings can be explained by something that we were not able to consider in our analysis,” Borgi said.

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For now, Gottschall-Pass says Canadians shouldn’t worry about eating potatoes as long as they’re prepared carefully and aren’t smothered in unhealthy toppings and garnishes.

Potatoes are packed with potassium, vitamins B6, B3 and C, manganese and fibre (especially if you eat the skin).

carmen.chai@globalnews.ca
Follow @Carmen_Chai